Atomic-scale investigation on endurance mechanism of the GeTex-based OTS device by Si doping

Abstract

The Ovonic Threshold Switching (OTS) devices have attracted great attention as a candidate for suppressing leakage current on 3D-PCM. However, the theories about improving the endurance of OTS devices are still lacking. Based on the theoretical study, we provide a strategic guide for developing high-endurance Si-doped GeTex devices efficiently. The contribution of Si doping on the bonding properties and atomic structure is systematically investigated by first-principal calculation. As we predicted, the strong Si–Te bonds, increasing tetrahedrons, and fewer 4-fold rings are found in the a-GTSi structure, where most of the atoms obey the “8-N” rules and transform toward 4-coordination to stiff the disordered structure. All these structural characteristics confirm that Si atoms improve amorphous stability. With the added Si atoms, the XPS identifies that Si–Te bonds and increasing numbers of the Ge–Te bonds are present in the Si: GeTex film. Experimentally, the device performs excellent endurance (∼107 cycles), which is well in agreement with the theory. This work provided an efficient approach to developing high-performance OTS devices.